NX series hydraulic heat questions.

[justman777]

Look on the right side behind the step and see what size hoses yours have. I'm curious.

All of the hoses are 3/8. At least, that's what it says in the installation manual. It looks like the nipples to install in the valve body are also 3/8.

I installed mine myself because I bought the tractor and took it home the same day. Dealer drop shipped the kit to me. I've mentioned before a few times that I was thoroughly underwhelmed with the installation instructions. Took me nearly 7 hours to get it installed, primarily because I has having to interpret instructions.

 

[TN8Man]

Is there a hydraulic fluid temp sensor that can be installed on the NX tractor's?

Or is there a hydraulic fluid temp sensor already installed that is monitored by the ecu system?

What is the maximum hydraulic fluid temp for the fluid you are using where degradation and seal damage occurs? Is it 180F?

 

[dusty3030]

Is there a hydraulic fluid temp sensor that can be installed on the NX tractor's?

Or is there a hydraulic fluid temp sensor already installed that is monitored by the ecu system?

What is the maximum hydraulic fluid temp for the fluid you are using where degradation and seal damage occurs? Is it 180F?

Good questions. I don't know about the temp sensor. The way I discovered it was just because I was checking everything over well and getting familiar with the new tractor. I was feeling what I felt like was a lot of heat off the rear end and that area so I grabbed my thermometer and started checking things out.

As far as the factory fill fluid, I don't know what they used. After I had seen 210 one day and 220 the next after mowing only one hour each session I started digging to get to the bottom of this. I was worried about the fluid that was in there and I already had 15 gallons of Kubota SUDT2 so I ordered filters and changed it. FWIW there weren't any metal chunks or anything else that concerned me on the magnet that goes in the suction filter so I'm hoping I caught this before I fried anything. I have 18.5 hours on the tractor now so I'm optimistic I did.

After taking the factory third function out of the circuit and connecting the line that goes back to the rear remote / three point back to the loader valve power beyond with it's original elbow fitting I mowed in the exact same field, same ambient heat conditions for approximately the same amount of time as the other two sessions and recorded 169 degrees. A 40 to 50 degree swing.

 

[justman777]

Good questions. I don't know about the temp sensor. The way I discovered it was just because I was checking everything over well and getting familiar with the new tractor. I was feeling what I felt like was a lot of heat off the rear end and that area so I grabbed my thermometer and started checking things out.

As far as the factory fill fluid, I don't know what they used. After I had seen 210 one day and 220 the next after mowing only one hour each session I started digging to get to the bottom of this. I was worried about the fluid that was in there and I already had 15 gallons of Kubota SUDT2 so I ordered filters and changed it. FWIW there weren't any metal chunks or anything else that concerned me on the magnet that goes in the suction filter so I'm hoping I caught this before I fried anything. I have 18.5 hours on the tractor now so I'm optimistic I did.

After taking the factory third function out of the circuit and connecting the line that goes back to the rear remote / three point back to the loader valve power beyond with it's original elbow fitting I mowed in the exact same field, same ambient heat conditions for approximately the same amount of time as the other two sessions and recorded 169 degrees. A 40 to 50 degree swing.

Couple of other historical threads indicated that ambient temp plus 100 degrees is about right for hydraulic oil.

 

[MinnesotaEric]

Should be using a DO3 subplate which is rated at 10 gpm. 10 GPM will restrict but only at WOT. For me, here in north-central Minnesota, heat in the hydro in the winter is desirable. During the summer, I set my RPM at 2000 to run my Woods BB720X, and the only time I'm at wide-open throttle is when using my snowblower in the winter. Most of the time, I'm using the throttle feature (like driving a car--sorta). All to say heat from a slightly restricted subplate to run an electric over hydraulic two-way valve for a third function isn't an issue.

 

[TN8Man]

Good questions. I don't know about the temp sensor. The way I discovered it was just because I was checking everything over well and getting familiar with the new tractor. I was feeling what I felt like was a lot of heat off the rear end and that area so I grabbed my thermometer and started checking things out.

As far as the factory fill fluid, I don't know what they used. After I had seen 210 one day and 220 the next after mowing only one hour each session I started digging to get to the bottom of this. I was worried about the fluid that was in there and I already had 15 gallons of Kubota SUDT2 so I ordered filters and changed it. FWIW there weren't any metal chunks or anything else that concerned me on the magnet that goes in the suction filter so I'm hoping I caught this before I fried anything. I have 18.5 hours on the tractor now so I'm optimistic I did.

After taking the factory third function out of the circuit and connecting the line that goes back to the rear remote / three point back to the loader valve power beyond with it's original elbow fitting I mowed in the exact same field, same ambient heat conditions for approximately the same amount of time as the other two sessions and recorded 169 degrees. A 40 to 50 degree swing.

Looking into the testing of hydraulic fluids I found that the standard test for viscosity and viscosity index VI (change in viscosity relative to temperature change) is performed at 40C (104F) and 100C (212F). While Kubota SUDT2 has a higher viscosity index at 199 VI (higher is better) than others (lets say Traveller Premium Hydraulic Fluid @ 135 VI) they are both rated above 110 viscosity index (highest rating). The interesting thing is that Traveller Premium Hydraulic Fluid performed better (higher viscosity) at 100C (212F) than Kubota SUDT2 but Kubota SUDT2 had a higher viscosity at 40C (104F). The good news is that most hydraulic fluids available are tested per ASTM D-445 and ASTM D-2270 so as long as the viscosity index is above 110 they should all perform very well.

I also found out these popular name brands are made at factories that usually have the same exact fluid sold under a less popular name and for less cost. The MSDS will usually point you to that information.

 

[Bavarian]

There was definitely a restriction that caused heat. It might have been the valve itself or the combination of hoses and valve.
When I worked in hydraulics 30 years ago, our threshold was 90 Celsius for the hydraulic oil. That compares to 194 farenheit. It's the rubber O-rings that get brittle over time. 250 farenheit was the next threshold. Oil would lose it's lubrication and cause internal damage.
Considering the short amount of time (18.5.hours) and no metal found on the magnet, the OP should be fine.

 

[TN8Man]

There was definitely a restriction that caused heat. It might have been the valve itself or the combination of hoses and valve.
When I worked in hydraulics 30 years ago, our threshold was 90 Celsius for the hydraulic oil. That compares to 194 farenheit. It's the rubber O-rings that get brittle over time. 250 farenheit was the next threshold. Oil would lose it's lubrication and cause internal damage.
Considering the short amount of time (18.5.hours) and no metal found on the magnet, the OP should be fine.

Good info!

Looking at the Kubota SUPER UDT2 UNIVERSAL TRANS-HYDRAULIC FLUID MSDS it lists 128C (262.4F) Calculated Flash Point.

 

[dusty3030]

Some things I've learned.
Looks like the hydraulics are all BSPP thread. I've confirmed with micrometer and thread pitch gauges. The linked specs from the valve manufacturer confirm this.

The ports on the third function valve are 3/8" BSPP.
The port coming out of the loader block power beyond is 1/2" BSPP.
The valve supplied with my tractor is max flow of 10.5 gallons (40 liters) per minute.

I'm going to try and salvage what I can. This would be fine on a smaller tractor in the Kioti line but not this one. I'm still not sure if they shipped the right kit or not. I was hoping to be able to maybe just change out the manifold but I think I will change out the whole valve and try and reuse the work lines out since that part of it is fine and already installed. Scouring Summit and Surplus center websites now for a suitable solution. Will report back when I have one.

CWS - HAWE Hydraulik

https://downloads.hawe.com/7/9/D7951CWS-en.pdf

 

[justman777]

Based on the info presented, is it worth it to do all that? I can understand if it was damaging stuff...but I don't see that the temp difference is enough to justify trying to modify how it's set up.

If nothing else, how about a bypass hose with a shut off valve? When you plan on using the third function, you could turn off the flow to the bypass, forcing the flow through the third function manifold. Not as convenient as simply getting in the tractor and going, but may be cheaper and less complicated. Thoughts?